1. Field of the Invention
The invention relates to apparatus for the transfer of a complete turbine module from a balancing machine to an engine and vice versa, the turbine rotor being secured to the transmission shaft of the engine by an array of tie bolts and a method of operating the apparatus.
2. Summary of the Prior Art
Engineers assembling turbine engines, particularly those intended for aircraft, have attempted to simplify maintenance operations so that they can be effected even in scantilly equipped workshops. One solution consisted in forming the sub-assemblies in modular form, the more important modules being such as to enable their ready replacement. However, the production of the turbine stage as a module has not totally resolved the problem. In practice the high speeds to which the rotor blades are subjected necessitate very precise balancing, which balancing must not be disturbed during the reassembly of the turbine on the other sub-assemblies or modules of the engine. The current solution consists in balancing the rotor alone on a balancing machine, then reassembling the rotor on the engine, the stator stages being assembled after the coupling of the rotor to the engine shaft. A similar method is described in U.S. Pat. No. 3,916,495 for assembling a turbine rotor constituted by two interconnected disks and to the engine transmission shaft by an axial array of tie-bolts. The rotational torque is transmitted between the disks and between one disk and the shaft by drive rings with conical teeth. The rotor is balanced on a machine the shaft of which has the same characteristics as those of the engine and of drive ring of which is identical. The balancing is effected in a known manner and is controlled by the addition of masses, having the form of plugs, clamped under the nuts of the tie bolts.
After balancing, the rotor is removed from the machine and can be reassembled on an engine without the necessity of rebalancing if the relative positions of the balancing masses are maintained.
The balancing of the rotor independently of other parts of the engine constitutes an appreciable simplification, since it enables maintenance in workshops which do not have a balancing machine. However, the mounting, after assembly of the rotor on its shaft, of stator blades can be the cause of damage to the labyrinths as a result of extremely small clearances and can cause a loss which is not negligible, in the efficacy of the assembly.
The apparatus and the method according to the invention have as their objective the balancing of a turbine rotor in its stator. The assembly constituting the turbine module can be readily coupled to a shaft while avoiding unbalancing of the rotor and/or damaging of the labyrinths. These results are obtained thanks to the maintenance devices and transport devices enabling the security of the balancing and the guidance of the module during its mounting in the engine.